From the time at which the river Tiber became the line of demarcation
between Etruria on the one side and Umbria and Latium on the other,
peaceful relations probably upon the whole prevailed in that quarter,
and no essential change seems to have taken place in the boundary
line, at least so far as concerned the Latin frontier.

Vividly
as the Romans were impressed by the feeling that the Etruscan was
a foreigner, while the Latin was their countryman, they yet seem
to have stood in much less fear of attack or of danger from the
right bank of the river than, for example, from their kinsmen in
Gabii and Alba; and this was natural, for they were protected in
that direction not merely by the broad stream which formed a natural
boundary, but also by the circumstance, so momentous in its bearing
on the mercantile and political development of Rome, that none of
the more powerful Etruscan towns lay immediately on the river, as
did Rome on the Latin bank.

The Veientes were the nearest to the
Tiber, and it was with them that Rome and Latium came most frequently
into serious conflict, especially for the possession of Fidenae,
which served the Veientes as a sort of -tete de pont- on the left
bank just as the Janiculum served the Romans on the right, and
which was sometimes in the hands of the Latins, sometimes in those
of the Etruscans. The relations of Rome with the somewhat more
distant Caere were on the whole far more peaceful and friendly than
those which we usually find subsisting between neighbours in early
times.